Quick answer
Category B generally covers passenger cars up to 3.5 t. A trailer up to 750 kg is often possible if the towing vehicle is allowed to tow it.
A trailer over 750 kg can still be possible with B if the permitted total weight of car and trailer together does not exceed 3.5 t. Above that, category BE becomes relevant.
What to check
Use the vehicle documents: towing capacity, trailer gross weight, tongue load and any train-weight limit. These figures matter more than rough estimates.
If unsure, pick a lighter trailer or ask the vehicle manufacturer, road traffic office or a qualified specialist.
B96 clarification
B96 appears in searches because of foreign rules. For Swiss rental copy, B versus BE under Swiss rules is the useful framing.
Before booking, check licence, vehicle limits, payload and load securing. Do not drive a combination that requires a licence category you do not hold.